On the perceptual organization of speech.

Abstract

How does a perceiver resolve the linguistic properties of an utterance? This question has motivated many investigations within the study of speech perception and a great variety of explanations. In a retrospective summary 15 years ago, Klatt (1989) reviewed a large sample of theoretical descriptions of the perceiver's ability to project the sensory effects of speech, exhibiting inexhaustible variety, into a finite and small number of linguistically defined attributes, whether features, phones, phonemes, syllables, or words. Although he noted many distinctions among the accounts, with few exceptions they exhibited a common feature. Each presumed that perception begins with a speech signal, well-composed and fit to analyze. This common premise shared by otherwise divergent explanations of perception obliges the models to admit severe and unintended constraints on their applicability. To exist within the limits set by this simplifying assumption, the models are restricted to a domain in which speech is the only sound; moreover, only a single talker ever speaks at once. Although this designation is easily met in laboratory samples, it is safe to say that it is rare in vivo. Moreover, in their exclusive devotion to the perception of speech the models are tacitly modular (Fodor, 1983), whether or not they acknowledge it.Despite the consequences of this dedication of perceptual models to speech and speech alone, there has been a plausible and convenient way to persist in invoking the simplifying assumption. This fundamental premise survives intact if a preliminary process of perceptual organization finds a speech signal, follows its patterned variation amid the effects of other sound sources, and delivers it whole and ready to analyze for linguistic properties. The indifference to the conditions imposed by the common perspective reflects an apparent consensus that perceptual organization of speech is simple, automatic, and accomplished by generic means. However, despite the rapidly established perceptual coherence of the constituents of a speech signal, the perceptual organization of speech cannot be reduced to the available and well-established principles of auditory perceptual organization.

Lexical Information Drives Perceptual Learning of Distorted Speech: Evidence From the Comprehension of Noise-Vocoded Sentences.

“…Remez et al, 1994). Under extreme forms of distortion, this top-down support can produce dramatic changes to the percept evoked by a vocoded sentence.…”

“…For example, speech remains understandable when formants are resynthesized as sinusoids (Remez, Rubin, Berns, Pardo, & Lang, 1994;Remez, Rubin, Pisoni, & Carrell, 1981), a manipulation that removes most of the natural qualities of the human voice from a speech signal. Other manipulations have shown that dramatic alterations to both the temporal (Mehler et al, 1993;Saberi & Perrott, 1999) and spectral (Shannon, Zeng, Kamath, Wygonski, & Ekelid, 1995;Smith, Delgutte, & Oxenham, 2002) properties of speech do not substantially impair the intelligibility of spoken language when background noise is absent.…”

Multimodal perceptual organization of speech: Evidence from tone analogs of spoken utterances

“…For example, the resonances of a speech signal change in frequency and amplitude asynchronously, to different extents, and at different rates, and these physical conditions oppose grouping by Gestalt principles. The coherence of aperiodic bursts, aspiration and friction likewise defy the Gestalt grouping principles, due to their physical and auditory dissimilarity from the periodic portions of speech signals (see (Remez et al, 1994), for a detailed exposition). From this perspective, the perceptual organization of speech requires the establishment of coherence among dissimilar sensory elements whether sensation is unimodal and auditory or multimodal and auditor-visual.…”

“…Although Welch and Warren (1980) proposed that multimodal integration might depend on a common spatial locus for sound and sight, this premise falsely predicts failure of dichotic fusion of speech (Broadbent and Ladefoged, 1957;Remez et al, 1994), and the findings of a direct investigation of multimodal integration of spatially disparate visual and auditory sources of phonetic information (Bertelson et al, 1997). In phonetic perceptual organization, there does not appear to be a single simple factor that determines the formation of intermodal coherence.…”

“…This fact arguably demonstrates the limitations of Gestalt-derived auditory accounts of perceptual organization, which describe the integration of sensory constituents based on their similarity (Bregman, 1990), and probabilistic accounts of speech perception, which describe the integration of signal elements based on likelihood (Massaro, 1994). Instead, findings with sinewave replicas of speech appear to warrant an account of perceptual organization based on perceptual susceptibility to the unique spectrotemporal characteristics of a phonologically modulated source of sound (Remez et al, 1994). Perceptual organization of speech signals, in this view, occurs by virtue of a perceiver's sensitivity to patterned spectra despite the momentary dissimilarity among the constituents of the pattern, in contrast to the piecemeal assessment of elemental details of the acoustic stream which is central in prior accounts.…”